This invention relates to the preparation and composition of a powder capable of functioning as a stabilizing agent in a wide variety of products such as foods and cosmetics. In particular, this invention relates to coprocessing microcrystalline cellulose with maltodextrin to produce a dispersion that can be spray dried at high solids content to produce a free flowing powder.
Microcrystalline cellulose is an important component of many stabilizing agents and texture agents. However, when microcrystalline cellulose is prepared for use as a stabilizing agent and/or texture agent in a food or cosmetic, it must be coprocessed by drying with a material that acts a barrier dispersant. Unless a barrier dispersant is added, aggregation (hornification) occurs during dying, and the dried microcrystalline cellulose can not be readily redispersed. Dispersibility is essential for microcrystalline to function as a colloid in various applications, especially in the food area.
Durand, U.S. Pat. No. 3,539,365, discloses a process in which microcrystalline cellulose is coprocessed with carboxymethyl cellulose. This eliminates formation of undesirable aggregates on drying so that the dried product is easily redispersible in aqueous media. However, when carboxymethyl cellulose is coprocessed with microcrystalline cellulose by spray drying, concentrated solutions cannot be sprayed because of the high viscosity of concentrated carboxymethyl cellulose/microcrystalline cellulose solutions. Large volumes must be spray dried to obtain a given amount of a microcrystalline cellulose/carboxymethyl cellulose composition.
Therefore, a need exists for a method of producing microcrystalline cellulose that can be readily redispersed in aqueous media but does not require the processing of large volumes of liquid during spray drying.
This invention is a method of producing microcrystalline cellulose that can be readily redispersed in aqueous media but does not require the processing of large volumes of liquid during spray drying. The method comprises the steps of:
a) preparing an aqueous dispersion comprising maltodextrin and microcrystalline cellulose; and
b) spray drying the aqueous dispersion to produce a coprocessed microcrystalline cellulose/maltodextrin composition;
in which:
the maltodextrin comprises about 40% to about 60% by weight of the total maltodextrin and microcrystalline cellulose in the dispersion and the microcrystalline cellulose comprises about 40% to about 60% by weight of the total maltodextrin and microcrystalline cellulose in the dispersion;
the dispersion comprises about 10% to about 30% total solids; and
the coprocessed microcrystalline cellulose/maltodextrin composition is a free flowing powder.
In another embodiment, the invention is a dry blend comprising carboxymethyl cellulose and the coprocessed microcrystalline cellulose and maltodextrin composition.
This invention is particularly advantageous because the dispersion of microcrystalline cellulose and maltodextrin can be spray-dried at a solids content of up to about 30%. If carboxymethyl cellulose were used in place of maltodextrin, the through-put would be much lower because microcrystalline cellulose/carboxymethyl cellulose dispersions of this concentration cannot be spray dried. The invention reduces processing costs because the volume of mixture that must handled and the volume of water to be evaporated are greatly reduced.
When dispersed in a liquid, a coprocessed microcrystalline cellulose/maltodextrin composition will not substantially increase the viscosity of the liquid. However, when carboxymethyl cellulose is added, the viscosity of the liquid will increase and the composition will be stabilized.
All percentages set forth in the specification and claims are percentages by weight unless otherwise indicated.
A coprocessed microcrystalline cellulose/maltodextrin composition may be prepared by preparing an aqueous dispersion of microcrystalline cellulose and maltodextrin and spray drying the dispersion. Maltodextrin serves as a barrier dispersant to preserve the colloidal properties of the microcrystalline cellulose when the combination of materials is spray dried. It prevents hornification of the microcrystalline cellulose particles during spray drying and when being redispersed in a liquid.
The maltodextrin should have a dextrose equivalent (DE) of from about 4 to about 20. Generally, the higher the dextrose equivalent, the higher the solubility of the maltodextrin in water. However, if the dextrose equivalent exceeds 20, then the resultant coprocessed product might be too sticky to be of commercial use. If the dextrose equivalent is below about 4, the solubility of a liquid dispersion will be adversely affected so that the dispersion might be too viscous to process.
Microcrystalline cellulose may be obtained from a raw material such as wood, wood pulps such as bleached sulfate and sulfate pulps, cotton, flax, hemp, bast or leaf fibers, regenerated forms of cellulose, soy hulls, corn hulls, nut hulls, and the like. It is generally prepared from the raw material sources by a combination of a chemical degradation and mechanical attrition. Chemical degradation may be accomplished by any of several well-known methods. For example, the raw material may be rendered into a cellulose rich pulp, and the pulp hydrolyzed with dilute mineral acid. Partial removal of water by, for example, filtration produces a wet cake.
Wetcake is sheared to reduce the average particle size of from about 0.1 to about 10 microns. Shearing of the cellulose particles to form colloidal particles may be accomplished using any suitable apparatus such as a Silverson(copyright) mixer. The choice of mixer will be apparent to one skilled in the art taking into consideration the particle size desired. The amount of microcrystalline cellulose that may be present may vary widely but is preferably from about 62% to about 86%.
The aqueous dispersion containing maltodextrin and microcrystalline cellulose may be prepared by shearing microcrystalline cellulose wetcake in a mixer, such as a Silverson(copyright) mixer, adding the maltodextrin, and mixing to produce a uniform composition. If necessary, water is added to the dispersion to produce a dispersion with the desired solids content. The maltodextrin comprises about 40% to about 60% of the total microcrystalline cellulose and maltodextrin in the dispersion and the microcrystalline cellulose comprises about 40% to about 60% of the total microcrystalline cellulose and maltodextrin in the dispersion. When the coprocessed composition comprises less than 40% by weight maltodextrin, the it will not be satisfactory because the maltodextrin will not be present in an amount sufficient to operate as a barrier dispersant and prevent agglomeration of the microcrystalline cellulose particles. If more than about 60% of the maltodextrin is present in the coprocessed composition, the amount of microcrystalline cellulose present will be insufficient to obtain the proper colloidal content in a liquid.
In a preferred embodiment, microcrystalline cellulose and maltodextrin are each present in an amount of from about 45% to about 55%, based on the total amount of microcrystalline cellulose and maltodextrin present in the composition. In a more preferred embodiment, microcrystalline cellulose and maltodextrin are each present at about 50%.
The dispersion is then spray dried to form a free flowing powder. The dispersion is typically spray dried at an inlet temperature of from about 200xc2x0 C. to about 280xc2x0 C. and an outlet temperature of from about 100xc2x0 C. to about 120xc2x0 C. The dispersion typically comprises about 10% to 30% solids (i.e., maltodextrin and microcrystalline cellulose), preferably about 20% to about 30% total solids, and more preferably about 25% to about 30% total solids. Following spray drying, the microcrystalline cellulose/maltodextrin composition typically comprises about 3% to about 5% water.
If the microcrystalline cellulose/maltodextrin composition is used by itself, there is no substantial increase in the viscosity of a liquid to which it is added. However, when it is desired to prepare a gravy or soup, for example, it usually is desired to increase the viscosity beyond that of a water-like consistency. The coprocessed microcrystalline cellulose/maltodextrin composition may have carboxymethyl cellulose added to it to increase the viscosity of the product.
Carboxymethyl cellulose is prepared in any suitable manner to yield a free flowing powder and added to the coprocessed microcrystalline cellulose/maltodextrin composition. A high viscosity carboxymethyl cellulose, such as AQUALONG(copyright) 7HF carboxymethyl cellulose or AQUALON(copyright) 7H carboxymethyl cellulose, is preferred.
Carboxymethyl cellulose can be added to the microcrystalline cellulose/maltodextrin composition as a free flowing powder and dry blended therewith. Addition of carboxymethyl cellulose to the coprocessed microcrystalline cellulose/maltodextrin composition provides stability to the microcrystalline cellulose dispersion and increases the viscosity of the liquid to which it is added.
When the resulting composition, which comprises carboxymethyl cellulose and coprocessed microcrystalline cellulose/maltodextrin, is dispersed in a liquid, the carboxymethyl cellulose and microcrystalline cellulose form a network that provides the viscosity and the rheology desired for the product to which it is added. However, the carboxymethyl cellulose will not form the network unless hornification of the microcrystalline cellulose has been prevented by coprocessing of the microcrystalline cellulose with maltodextrin.
Alternatively, the coprocessed microcrystalline cellulose/maltodextrin composition may be dispersed in a liquid and carboxymethyl cellulose dispersed in the same liquid.
Carboxymethyl cellulose may be added in an amount of from about 1% to about 20% of the total weight of the dry blend, typically about 2% to about 15%, preferably about 4% to about 10% of the total weight of the dry blend. The amount of carboxymethyl cellulose added depends on the end use for the composition and the viscosity desired for the final product.
The dry blend typically comprises about 1% to about 20% carboxymethyl cellulose and about 80% to 99% of the coprocessed microcrystalline cellulose/maltodextrin composition, based on the total amount of carboxymethyl cellulose and coprocessed microcrystalline cellulose/maltodextrin composition in the dry blend. Typically no other materials, other than small amounts (typically about 3% to about 5%) of water that were present in either the carboxymethyl cellulose and/or of the coprocessed microcrystalline cellulose/maltodextrin composition, are present in the dry blend.
The dry blend typically comprises about 1% to about 20% carboxymethyl cellulose, about 32% to about 60% microcrystalline cellulose, and about 32% to about 60% maltodextrin, based on the total amount of carboxymethyl cellulose, microcrystalline cellulose, and maltodextrin in the dry blend of carboxymethyl cellulose and coprocessed microcrystalline cellulose/maltodextrin composition. The dry blend preferably comprises about 2% to about 15% carboxymethyl cellulose, about 34% to about 59% microcrystalline cellulose, and about 34% to about 59% maltodextrin, based on the total amount of carboxymethyl cellulose, microcrystalline cellulose, and maltodextrin in the dry blend. More preferably, the dry blend comprises about 4% to about 10% carboxymethyl cellulose, about 36% to about 58% microcrystalline cellulose, and about 36% to about 58% maltodextrin, based on the total amount of carboxymethyl cellulose, microcrystalline cellulose, and maltodextrin in the dry blend. Even more preferably, the dry blend preferably comprises about 4% to about 10% carboxymethyl cellulose, about 40% to about 53% microcrystalline cellulose, and about 40% to about 53% maltodextrin, based on the total amount of carboxymethyl cellulose, microcrystalline cellulose, and maltodextrin in the dry blend.
The compositions may be added to a food or cosmetic product in an amount of from about 0.1% to about 20%. The amount of the composition added to the food or cosmetic product will depend on the food product to which it is added. Whether the microcrystalline cellulose/maltodextrin composition is used or whether the three component system, which also comprises carboxymethyl cellulose, is used will depend upon the product to which they will be added. For example, in the preparation of a dry powdered chocolate drink, the microcrystalline cellulose/maltodextrin composition and carboxymethyl cellulose would be added to stabilize the dry powdered drink so that the solids would not settle out when a liquid, such as milk, was added. In the preparation of salad dressing, the dry blend may be used to increase viscosity and to obtain proper mouthfeel and texture modification. The microcrystalline cellulose composition and the dry blend may be used in other products such as sour cream, yogurt, yogurt drinks, stabilized frozen yogurt, whipping creams, puddings, peanut butter and in low moisture food systems. They may also be used as an excipient for chewable tablets in pharmaceutical applications as well as for cosmetic applications, for example, in cold cream formulations and tooth paste.
The invention will now be illustrated with the following Examples, which illustrate but do not limit the invention.